The invention relates to an automatic testing apparatus for testing the circumferential spacing and for ascertaining deviations in concentricity, tooth thickness and tooth gap in gears. In this apparatus, the gear is indexable from one measuring position to another by means of its own power source or, as needed, is caused to rotate via a slip coupling, and on the apparatus frame a primary slide is displaceable by a drive mechanism substantially radially toward and away from the gear between optionally adjustable stops. The positioning of the gear for the measuring processes is effected by means of an incremental rotational drive means rotationally connected with the gear. A feeler for the successive ascertainment of measured values on the right and left tooth flanks is also disposable in one measurement increment on the primary slide. Means advancing from one tooth gap to the next and intended for automatically inserting the feeler into the measurement position and retracting it back out of this position are also included, as are means for controlling the pickup, emission and further processing of the measured values in a manner that is coordinated therewith.
U.S. Ser. No. 477,785 addresses the disadvantage of a known apparatus, which is that two complete gear revolutions are required in order to ascertain the error in circumferential spacing; moreover, to accomplish this, the measuring feeler must be transferred from one tooth flank to the other between the two revolutions. Solutions are proposed in the above-identified application for accomplishing in a single gear revolution the testing of circumferential spacing of both the right and the left flanks of the gear, thereby reducing the testing time by half as compared with then-known apparatus. A method is also described which makes it possible, with this new circumferential spacing test apparatus, to measure deviations in gear concentricity, tooth thickness and tooth gaps as well, thereby obviating the use of a second apparatus therefor. Among other features, the method includes one in which a measuring feeler, located in one measuring position in a tooth gap, is indexable from the left to the right tooth flank or vice versa.
This indexing action can result in recoiling with respect to the measuring feeler, which may possibly interfere with the pickup of the measured value.